This book proposes a framework for describing languages through the description of relationships among lexicon, morphology, syntax, and phonology. The framework is based on the notion of formal coding means; the principle of functional transparency; the notion of functional domains; and the notion of systems interaction in the coding of functional domains. The study is based on original analyses of cross-linguistic data. The fundamental finding of the study is that different languages may code different functional domains, which must be discovered by analyzing the formal means available in each language. The first part of the book proposes a methodology for discovering functional domains and the second part describes the properties of various functional domains. The book presents new cross-linguistic analyses of theoretical issues including agreement; phenomena attributed to government; nominal classification; prerequisites for and implications of linear order coding; and defining characteristics of lexical categories. The study also contributes new analyses of specific problems in individual languages.